I. Field of the Invention
The present invention generally relates to a process for purifying contaminated water and to an apparatus for performing that process. The present invention provides particularly suitable methods and apparatus for purifying waste water containing fatty acids. More specifically, the present invention is directed to methods and apparatus for purifying contaminated water, e.g., waters containing suspended organic colloidal emulsions or suspensions such as effluents from meat processing plants, dairies, cheese processing plants, bakeries, chemical plants and petroleum plants and effluents including raw sewage.
II. Description of the Background
Economical and efficient methods and apparatus for purifying contaminated water, particularly water containing fatty acids, have long been sought. Many industrial facilities, particularly facilities plagued with fatty acid wastes, have long sought improved methods for purifying waste water.
An exemplary method and apparatus for achieving the desired purification were disclosed in U.S. Pat. No. 4,802,991 by Miller. The '991 patent illustrated and described a method of water purification wherein fatty acids contaminating the water are combined with metallic ions released from electrodes during electrolysis to form hydrophobic, metallic soaps. According to the process described by Miller, bivalent or trivalent metal ions released from electrodes during electrolysis combine with the fatty acids to form an insoluble flocculant. The flocculent, in turn, entrained or absorbed other impurities present in the contaminated water. Thus, the flocculant served as a transport medium to remove not only fatty acids, but also other impurities from the water.
In order to ensure continuous production of ions, the electrodes in the apparatus disclosed by Miller were disposed in a moving bed of solid particles. Those solid particles were kept in motion by the flow of process water through the electrolysis chamber in order to continuously abrade and clean the electrode surfaces. The flocculant and entrained impurities were directed to a flocculation/separation basin where the flocculant and entrained impurities were separated by flotation, leaving purified water for withdrawal from the basin.
The method and apparatus described by Miller in the '991 patent, while technically elegant, have found only limited use. Systems employing iron electrodes, while functional, proved unacceptable due to the difficulty in removing ferrous hydroxide from the purified water. Systems employing aluminum electrodes were found to be uneconomical due to the high cost for both electrodes and labor incurred for replacement of spent electrodes. Accordingly, use of the method and apparatus disclosed in the '991 patent was restricted to applications where other methods were cost prohibitive.
Thus, the water purification industry has continued to seek new and improved methods for removing fatty acids and other contaminants from water. Accordingly, there has been a long-felt but unfulfilled need for more economical, more efficient and more convenient methods for purifying water, particularly water contaminated with fatty acids and other contaminants. The present invention solves those needs.